On Endings

[dukealien]

(Part III of a [currently 3-part] series addressed to a young student)

III. On Endings

Beloved, eventually you will find yourself  nice line break... "find yourself/"
shedding aspects of yourself with each passing year.
Don’t worry: like Medea, you are becoming yourself,
growing into yourself. Discovering what you are capable of.  More like discarding inhibitions or ethics:  a little worrisome here.
For better and for worse, for each discovery is  different word for the second use of "for" here (first is necessary), for variety
a closing door. One night you will go out
and come home late and drunk and happy,
music still ringing in your ears, a stranger in your arms,
for the last time. One evening after the long tedious work day 
you will be done with disco naps, content to relax into quietude  I don't get a picture from "disco naps;" "relax into quietude" seems weak, maybe a more unusual word than "relax" since "quietude" is nice here
or comfortable companionship. One day you will look out
over the fog rolling in and wish you had fewer friends.  lose "the?"  Otherwise an elegant line.
Not even knowing that you want that yet, or that you have stopped
wanting that other thing, that you are done with that.  Think I see what repeated "that" is trying to do in these two lines, but it doesn't quite work for me.  Some could be replaced with "this" or "it" for variety... not all?

One morning you will wake up, no longer young,  lose "up?"  (Don't mind me, I just like iambs)
and discover that you must have your coffee in a particular mug,  lose "that," maybe find better word than "particular"
that you have made a routine, that you are done with line break after "done" for effect
a life in which your suitcase is always ready, and all that you own  could simplify, e.g. "with life, your suitcase always ready, all you own"
fits within it easily. You will find that you want to stay rather than go,
at last. Each time a last time, though you don’t know it at the time.  lose "it," a few other words here
Each time a casting off of aspects of yourself. Possibilities. This then simplify - "a casting off of aspects, possibilities."
is aging: becoming more purely yourself, letting fall
the faces you now are trying on until "now" seems unnecessary here
one day in ballet class you will be so focused, so fully yourself,  perhaps "you'll" for rhythm, and is "fully" necessary?
that you don’t even notice the slight ache here's a place for "that," replacing "the"
in your knees, the loud pops in your hips 
at the first grande plié, that you concentrate so hard on the frappés
that it is days before you notice the bruise at your ankle  "notice bruising at your ankle" perhaps
from your foot swinging out and in, pushing off 
against the floor, and back in, 
devant, de côté, derriere, and out, and in.
So focused that you feel yourself merging into the is this "the" necessary?
centuries of history of people doing exactly this, 
exactly this way. Plié. Tendu. Dégagé. One day
there will even be a last ballet class, you will leave
the studio with the usual casual farewells, and  is "the usual" necessary?
never return, never hold that barre again,
never correct your placement in that mirror
again, and you will be one of a thousand million dancers
who left the studio for the last time, all unaware of the ending,  perhaps "heedless" for this "unaware" for variety?
all unaware that that pirouette was your last pirouette. 

One evening, if you are lucky, you will leave a place
you have loved, where you have learned and loved, 
where you know even the angle of light of the sun as it sets  this does come across angular, which is good - could it be more brief?
in every season, and where to find any day’s last sunbeam. Even for that place
there will be a last time you leave it, even though you won’t even notice
the door as it swings smoothly shut behind you,
and the voices of the crowds will blend into the noises of the street
like a photograph where you pushed the button just as someone jostled you,
so that none of the boundaries are clear, but everything blends 
into everything else and nothing is clearly itself.  Not getting the purpose of the blur here.  Yes, you won't specifically remember the last time - is that it?  What I mean is, the memory/vision metaphor seems a bit weak.  There *was* a last moment, like the green flash at sunset... you just won't remember it, only deduce later that it must have happened.
Even yourself, someday. Even that, remember.

This is all I want to tell you, beloved,
this is the secret to everything:

Not sure an intensive critique of this work is in range, but will give it a try.  Specifics above.

In general, I think I get the poem and the spirit in/with which it's offered.  The style is not unpleasant, and is consistent throughout.  My urging to use less repetition (and fewer "that" and "the" particularly) will tend to make it less professorial and more to-the-beloved, have to decide what you want.  Conversational, which you have, or more impactful and arresting, which may not be appropriate.

The reference to Medea made me think of Atropos (she of endings, and the third of the Moirai as this is the third in your series).